Aqueous formulations comprising at least two different polymers as aqueous dispersions

Abstract

The present invention relates to aqueous formulations comprising: i. at least one hydrophilic particulate polymer P1, as an aqueous dispersion, composed essentially of monoethylenically unsaturated monomers having a water-solubility in the range from 10 to 100 g/l (at 25° C. and 1 bar), and ii. at least one hydrophobic particulate polymer P2, as an aqueous dispersion, composed essentially of ethylenically unsaturated monomers having a water-solubility below 10 g/l (at 25° C. and 1 bar), the glass transition temperature T g 1 of the polymer P1 being less than 10 K different from the glass transition temperature T g 2 of the polymer P2.

We claim:  
     
       1. An aqueous formulation comprising a blend of an aqueous dispersion comprising: 
       i. at least one hydrophilic particulate polymer P1, as an aqueous dispersion, which is composed of ethylenically unsaturated monomers M comprising: from 20 to 100% by weight of at least one monoethylenic ally unsaturated monomer M1 having a water-solubility in the range from 10 to 100 g/l (at 25° C. and 1 bar),  
       from 0 to less than 80% by weight of one or more monoethylenically unsaturated monomers M2 having a water-solubility below 10 g/l (at 25° C. and 1 bar), and from 0 to 20% by weight of one or more monomers M3 which are different from the monomers M1 and M2, and  
       ii. at least one hydrophobic particulate polymer P2, as an aqueous dispersion, which is composed of ethylenically unsaturated monomers M′ comprising: from 0 to less than 20% by weight of one or more monoethylenically unsaturated monomers M1′ having a water-solubility in the range from 10 to 100 g/l (at 25° C. and 1 bar), from 80 to 100% by weight of at least one monoethylenically unsaturated monomer M2′ having a water-solubility below 10 g/l (at 25° C. and 1 bar), and from 0 to 20% by weight of one or more monomers M3′ which are different from the monomers M1′ and M2′, and  
       where the glass transition temperature T g 1 of the polymer P1 is less than 10 K different from the glass transition temperature T g 2 of the polymer P2 and where the proportions by weight of the monomers M1, M2 and M3 and of the monomers M1′, M2′ and M3′ respectively add up in each case to 100 by weight. 
     
     
       2. A formulation as claimed in  claim 1  wherein the monomers M1 and M1′ are selected independently of one another from methyl methacrylate, methyl acrylate, ethyl acrylate, n- and isopropyl acrylate, vinyl acetate, acrylonitrile, methacrylonitrile and N-vinylcaprolactam. 
     
     
       3. A formulation as claimed in  claim 1  wherein the monomers M2 and M2′ are selected independently of one another from C 2 -C 18 -alkyl methacrylates, C 4 -C 18 -alkyl acrylates, vinyl-aromatic monomers, C 2 -C 6 -olefins, conjugated dienes, vinyl chloride, vinylidene chloride and the vinyl esters of aliphatic C 3 -C 18  carboxylic acids. 
     
     
       4. A formulation as claimed in  claim 3  wherein the hydrophilic polymer P1 is composed of from: 
       from 20 to 80% by weight of methyl methacrylate as monomer M1,  
       from 20 to 79.9% by weight, of at least one monomer M2 selected from C 4 -C 8 -alkyl acrylates, styrene and α-methyl-styrene, and  
       from 0.1 to 10% by weight of at least one monomer M3,  
       or of: 
       from 20 to 90% by weight of vinyl acetate as monomer M1,  
       from 10 to less than 80% by weight of at least one monomer M2 selected from ethylene, the vinyl esters of aliphatic C 3 -C 12  carboxylic acids, and C 4 -C 8 -alkyl acrylates, and from 0 to 10% by weight of one or more monomers M3.  
     
     
       5. A formulation as claimed in  claim 3  wherein the hydrophobic polymer P2 is composed of: 
       from 2 to 19.9% by weight of methylmethacrylate as monomer M1′,  
       from 80 to 97.9% by weight of at least one monomer M2′ selected from C 4 -C 8 -alkyl acrylates, styrene and α-methylstyrene, and  
       from 0.1 to 10% by weight of at least one monomer M3′,  
       or of: 
       from 5 to less than 20% by weight of vinyl acetate as monomer M1′,  
       from 80 to 95% by weight of at least one monomer M2′,  
       selected from ethylene, the vinyl esters of aliphatic C 3 -C 12  carboxylic acids, and C 4 C 8 -alkyl acrylates, and from 0 to 10% by weight of one or more monomers M3′,  
       or of: 
       from 90 to 99.9% by weight of at least two different monomers M2′, selected from C 4 -C 8 -alkyl acrylates and C 2 -C 8 -alkyl methacrylates, and  
       from 0.1 to 10% by weight of at least one monomer M3′.  
     
     
       6. A formulation as claimed in  claim 1  comprising in addition to the polymers P1 and P2, at least one thickening polymer. 
     
     
       7. A formulation as claimed in  claim 6  comprising from 0.01 to 5% by weight, based on the overall weight of the formulation, of the thickening polymer. 
     
     
       8. A formulation as claimed in  claim 1  wherein the hydrophobic particulate polymer P2 has a weight-average particle diameter below 150 nm. 
     
     
       9. A formulation as claimed in  claim 1  wherein, the weight ratio of the polymers P1 to P2 is from 99:1 to 1:1. 
     
     
       10. A formulation as claimed in  claim 1  comprising in addition to the polymers P1 and P2 at least one solid in disperse form selected from organic or inorganic pigments and organic or inorganic extenders. 
     
     
       11. A method of coating a substrate, comprising applying to said substrate an aqueous formulation according to  claim 1 . 
     
     
       12. A formulation as claimed in  claim 1 , wherein the glass transition temperature Tg1 of the polymer P1 is not more than 5 K different from the glass transition temperature Tg2 of the polymer P2.